Light-emitting element and the manufacturing method thereof

• US 8,704,257 B2
• Filed: 02/07/2011
• Issued: 04/22/2014
• Est. Priority Date: 03/31/2009
• Status: Active Grant

• Current Assignee: Epistar Corporation
• Original Assignee: Epistar Corporation
• Inventors: Hsu, Chia-Liang, Yao, Chiu-Lin, Hsu, Tzu-Chieh, Huang, Chien-Fu, Chen, Shih-i
• Primary Examiner(s): Toledo, Fernando L
• Assistant Examiner(s): HALL, VICTORIA KATHLEEN
• Application Number:
  US13/022,098
• Publication Number:
  US 20110121291A1
• Time in Patent Office: 1,170 Days
• Field of Search: 257/98, 257/E33.001, 257/E33.055, 257E33067-E33073, 257/99, 438/22, 438 26- 29, 438/33, 438/36, 438/39, 438 42- 46, 438/116, 438/FOR.104
• US Class Current: 257/98
• CPC Class Codes: H01L 33/0093 Wafer bonding; Removal of the growth substrate
• CPC Class Codes: H01L 33/145 with a current-blocking structure
• CPC Class Codes: H01L 33/22 Roughened surfaces, e.g. at the interface between epitaxial layers
• CPC Class Codes: H01L 33/38 with a particular shape
• CPC Class Codes: H01L 33/46 Reflective coating, e.g. dielectric Bragg reflector

Abstract

A light-emitting element includes a light-emitting stack for emitting light and a substrate structure including: a first substrate disposed under the light-emitting stack and having a first surface facing the light-emitting stack; and a second substrate disposed under the light-emitting stack and having a second surface facing the light-emitting stack; and a reflective layer formed between the first substrate and the second substrate and having an inclined angle not perpendicular to the first surface.

Claims

1. A light-emitting element comprising:

a light-emitting stack for emitting light;

a transparent conductive layer disposed below the light-emitting stack;

an ohmic contact layer disposed between the light-emitting stack and the transparent conductive layer;

a substrate structure disposed under the light-emitting stack comprising;

a first substrate disposed under the light-emitting stack and having a first surface facing the light-emitting stack; and

a second substrate being a transparent substrate, disposed under the light-emitting stack, and having at least a second surface facing the light-emitting stack; and

a reflective layer formed between the first substrate and the second substrate and having an inclined angle not perpendicular to the first surface to reflect the light from the light-emitting stack, wherein the second surface of the second substrate is discontinuous in cross-section; and

a bonding structure formed between the substrate structure and the transparent conductive layer, wherein the bonding structure comprises a first conductive-attaching layer formed on the substrate structure and a second conductive-attaching layer formed on the bottom of the transparent conductive layer and wherein the bonding structure is offset laterally from the ohmic contact layer.

2. The light-emitting element according to claim 1, wherein the second substrate surrounds the first substrate, and the cross section of the first substrate is a truncated triangle shape that has a length of a bottom surface wider than that of the first surface.

3. The light-emitting element according to claim 1, wherein the first substrate is a wedge-shaped substrate having two inclined surfaces on two sides thereof, and the second substrate is formed on the two inclined surfaces of the first substrate.

4. The light-emitting element according to claim 1, wherein the material of the first substrate comprises sapphire, Si, SiC, GaN, ZnO, GaP or ceramic, and the material of the second substrate comprises polyimide, BCB, PFCB, epoxy, acrylic resin, COC, PMMA, PET, PC, polyetherimide, fluorocarbon polymer, silicone resin, glass, Al₂O₃, SiO₂, TiO₂, SiN_x, or SOG.

5. The light-emitting element according to claim 1, wherein the first conductive-attaching layer comprises a first metal-attaching layer formed on the first surface of the first substrate, and the second conductive-attaching layer comprises a second metal-attaching layer formed on the bottom of the transparent conductive layer.

6. The light-emitting element according to claim 5, wherein the material of the first substrate comprises Si, GaN, ZnO or GaP, and the material of the second substrate comprises polyimide, BCB, PFCB, epoxy, acrylic resin, COC, PMMA, PET, PC, polyetherimide, fluorocarbon polymer, silicone resin, glass, Al₂O₃, SiO₂,TiO₂, SiN_x, or SOG.

7. The light-emitting element according to claim 5, wherein a reflective index of the second conductive-attaching layer is higher than that of the first conductive-attaching layer.

8. The light-emitting element according to claim 1, wherein the first conductive-attaching layer comprises a first transparent-conductive bonding layer formed on the substrate structure, and the second conductive-attaching layer comprises a second transparent-conductive bonding layer formed on one side of the light-emitting stack.

9. A manufacturing method of a light-emitting element comprising steps of:

providing a first substrate, and forming a recess structure on a surface thereof for defining a plurality of protrusions, wherein each side wall of the protrusions is not perpendicular to a bottom surface of the first substrate;

forming a reflective layer conforming to the surface of the first substrate;

providing a second substrate being transparent and formed in the recess structure of the first substrate, thereby forming a substrate structure;

providing a light-emitting stack; and

providing an adhesive layer attaching the light-emitting stack to the substrate structure.

10. The method of claim 9, wherein the first substrate comprises a silicon substrate, the recess structure is formed by etching, and each side wall of the protrusions comprises an inclined angle with respect to the bottom surface of the first substrate, and the inclined angle is formed along an exposed silicon crystal lattice, the exposed silicon crystal lattice resulting from the etching of the silicon substrate.

11. The method of claim 9, wherein the process for forming the second substrate further comprises:

filling a transparent liquid material in the recess structure;

solidifying the transparent liquid material; and

performing a polishing process for removing the excess of the second substrate.

12. The method of claim 11, wherein the adhesive layer comprises an insulating-adhesive layer.

13. The method of claim 12, wherein the insulating-adhesive layer comprises silicon resin, BCB, epoxy, polyimide, or PFCB.

14. The method of claim 9, wherein the process for providing the adhesive layer to attach the light-emitting stack to the substrate structure further comprises:

forming a first metal-attaching layer on each top surface of the protrusions of the first substrate;

forming a plurality of second metal-attaching layers on a bottom of the light-emitting stack, and performing an alloying process between the first metal-attaching layer and the second metal-attaching layer, and attaching the second substrate to the bottom of the light-emitting stack at the same time.

15. The method of claim 9, wherein the process for providing the adhesive layer to attach the light-emitting stack to the substrate structure comprises:

forming a first transparent-conductive bonding layer on the substrate structure;

forming a second transparent-conductive bonding layer on a bottom of the light-emitting stack; and

attaching the first transparent-conductive bonding layer to the second transparent-conductive bonding layer.